WASHINGTON – The home of the future won't look any different from today's models. But it will be all new on the inside.

In one conception, the future home will anticipate the changing needs of its owners, with movable walls that adjust to fit their lifestyles so that they never outgrow their homes. Sometime soon, houses also will be able to accommodate changes in technology, and components will come in standard sizes so that they can be built fast.

How fast? How does 20 days from start to finish grab you?

This is just one vision of an innovative, futuristic "concept house" unveiled last summer by the Partnership for Advancing Technology in Housing, or PATH, a government-supported program that seeks to accelerate the use of innovative technologies.

PATH, which is administered by the Department of Housing and Urban Development (HUD), is in the process of developing multiple futuristic designs for urban, infill and rural markets under the concept-house program.

The very first model home suggests changes in design and construction techniques that "hold enormous potential" for improving housing, says HUD General Deputy Assistant Secretary Darlene Williams.

Take flexibility – or, more accurately, the lack thereof.

Today's houses are largely unalterable. Yes, you can add on, but that's often an expensive proposition.

You might be able to change how you utilize a particular room, turning an extra, unused bedroom into a home office, for example. But you can't move that room to where it will work best for you or your family, and you can't add up-to-date, high-speed transmission lines without poking holes in your wall or having a jumble of cables lying around.

The concept house changes that. It was designed by Torti Gallas and Partners, a Silver Spring, Md., architectural firm and a leader in modern urban planning, to have the quality and curb appeal of a custom-built home. But it is adaptable to the way you live – throughout your lifetime.

Today's floor plans rarely follow the same course as life plans. But in the flexible home of the future – circa 2010 or so, PATH hopes – you will be able to push walls around to accommodate whatever changes come your way.

Rooms originally designed for entertaining can become more defined as your family grows. If a new baby is on its way, you can carve out a bedroom. Or perhaps you can add a study or mudroom.

Because additions and upgrades will be less costly and labor intensive, a small, starter home can grow to become a dream house as its owner's budget allows. And, as you grow older, the house will adapt to the kinds of additional supports and conveniences needed to reconcile with the limited mobility that is a part of old age.

Moreover, when a move to another residence in another location is dictated by personal circumstances, the flexibility that you enjoyed in your home assures its marketability, because the new owners will know going in that the floor plan can be whatever they need it to be.

All of this will be made possible by separating the home's electrical, plumbing, communication, and heating and air conditioning systems.

Currently, the systems that make our homes work are tangled together behind finished interior walls, rendering them out of date the moment they are built and making it both difficult and costly to upgrade.

Indeed, moving a wall today is often as daunting as moving a mountain, largely because of what is buried behind them. But by untangling the systems, the building envelope can be created for long-term durability, and the utilities can more easily keep pace with the advent of new technologies.

PATH believes this kind of "systems thinking," or "whole-house design," will prepare the house for whatever lies ahead. "Utility systems that are independent of the building's structure – and sometimes each other – mean less hassle and expense in future system repairs, replacements and upgrades," the consortium says.

For example, surface runways leading to a utility "chase" might allow easy access to electrical and communication wiring, and perhaps even plumbing, so owners or technicians can reach "inside" as easily as you now change a light bulb.

Not only will there will be no need to knock endless holes in walls when it's time to catch up with the latest advances in cable or data lines, it will be easier to remodel old rooms and even add new ones as the family grows and evolves.

"If we are thoughtful about where the utilities are placed, we can allow more flexibility to move things around without incurring major expense," says architect Tom Gallas.

Among the other novel ideas that would provide dedicated space for utilities include floor modules or specially designed ceiling tiles. Or how about no wires at all? Instead, electricity might be delivered through electro-textile fabric wall coverings, or electrical systems that are totally wireless.

The house of the not-too-distant future also relies heavily on factory-built components for greater precision and quality control.

The benefits of indoor fabrication have long been documented. Among other things, factories offer better working conditions, faster construction time, less expensive labor and less waste.

But soon, a variety of factories will deliver pre-built bits and pieces to the construction site, arriving exactly when they are needed and fitting together perfectly because the building business will have adopted a standard measurement system that harmonizes components and connections.

The result: Building is easier and more efficient. Like a child's building blocks, the pieces simply snap together, no matter how many factories supply no matter how many components.

At first blush, architect Gallas thought the idea of eliminating variations in size squelched all opportunity for creativity. But as he began to consider the idea, it started to make sense.

"What surprised me most about the process is that a more standardized approach to manufacturing components yielded more flexibility for the homeowner," he says. "For example, doors are standard width, but there are many different kinds of doors. You can vary the color, the material, the texture."

While other PATH concept houses are currently on the drawing board, this first one is notable if only because it offers ideas and concepts that can be incorporated into construction practices right now.

"I learned a ton," says Torti Gallas project manager Chris French. "The concept house offers a lot of commonsense tools that can be used right away. There are some challenges, yes. But there are a lot of things like horizontal access and multistory chases that seem to be very achievable."

There are numerous experimental housing initiatives taking place throughout the country. But PATH's is special. Because it looks at production and regulatory issues as well as design and technology, the program has a comprehensive aspect that none of the others offer.

Still, no builders have stepped forward to build it – at least not yet. But HUD's Williams, who said the unveiling was essentially a call to action for the home-building business, has vowed that it will be built.

"It is offered as a point of departure for serious inquiry into the future of home building," she said at the model's unveiling.